Process for making heat sealed ruffled articles



3 Sheets-Sheet 1 Aug. 16, 1955 L. c. HOSFIELD PROCESS FOR MAKING HEAT SEALED RUFFLED ARTICLES Original Filed Dec. '7, 1946 Aug. 16, 1955 L. c. HOSFIELD PROCESS FOR MAKING HEAT SEALED RUFFLED ARTICLES 3 Sheets-Sheet 2 Original Filed Dec. 7, 1946 ATTORNEY INVENTOR LEE C. HOSFIELD BY Aug; 16, 1955 L. c. HOSFIELD 2,715,597

PROCESS FOR MAKING HEAT SEALED RUFFLED ARTICLES Original Filed Dec. 7, 1946 3 Sheets$heet 3 Moveable 57201 21729 Slag g TT zIZ (70 24.21% Trams/725552012 Zine Z/d I INVENTOR LEE C. HOSFIELD United States Patent Ofiice 2,715,597 Patented Aug. 16, 1955 PROCESS FOR B IAKING HEAT SEALED RUFFLED ARTICLES Lee C. Hosfield, Parma, Ohio, assignor, by mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New York Application October 18, 1950, Serial No. 190,802, new Patent No. 2,666,472, dated January 19, 1954, which is a division of application Serial No. 714,832, Decembar 7, 1946, now Patent No. 2,555,409, dated June 5, 1951. Divided and this application June 26, 1953, Serial No. 364,367

6 Claims. (Cl. 154117) This invention relates to novel unitary heat-sealed rufiies and ruffled articles made from thermoplastic dielectric materials, and to a novel process and apparatus for making such unitary rufiies by spot-welding together successive folded-over portions of rufiled films, sheets, fabrics or other sheet-like elements of thermoplastic dielectric materials and, if desired, concurrently spot-welding successive folded-over portions of the latter articles to another sheet, film, fabric or other sheet-like element made from the same or another thermoplastic dielectric material.

A large variety of articles such as raincoats, aprons, umbrellas, window curtains, shower curtains, dry goods sundries and the like now are being made from thermoplastic resinous dielectric materials. in the manufacture of such articles it is common practice to unite the margins of two or more films by sewing the margins together, using thread of suitable material. Such operations involve the repeated puncturing of the sheeting by the fabricating needles at closely-spaced points, thereby weakening the material at and adjacent the seam. Moreover, the seam produced is stiff and incapable of yielding when subjected to stretching forces, so that sudden stresses sometimes tear the thread from the sheeting or break the thread after only a slight elongation of the films. This method of fabrication is not satisfactory, particularly for articles where strength, durability, or imperviousness to water or other liquids and gases are required.

For the purpose of providing a stronger article, processes have been developed whereby sheets or films to be united have flat overlapping margins pressed together to form a seam while being heated to suitable temperatures. Heat and pressure are applied by means of heated cooperating pressure rolls to form a continuous welded seam.

In recent years the so-called electronic method of heating has assumed importance as a source of the welding heat. Opposed pressure rolls serve as rotating electrodes in a high frequency electric circuit. The thermoplastic dielectric materials, while continuously pressed between the electrodes, are subjected to a high frequency electric field, thereby being softened and welded together. Continuous narrow welded areas which readily are visible are thus formed. Such methods require that the sheets to be united are of uniform thickness and free from wrinkles, etc.

There are a wide variety of articles made from thermoplastic dielectric materials which, to be satisfactory for the intended use, require the affixing to a sheet, film or fabric made of or containing a coating of a thermoplastic dielectric material, of ruflies of the same or an equivalent material. Among such articles may be mentioned window curtains, shower curtains, aprons and other articles of wearing apparel, shelf and table decorative strips and covers, and the like. There also is a demand for unitary rufiled articles made from such dielectric materials.

It is highly important that such ruflled articles have an attractive appearance and be of a uniform construction. The rufiled structure must be strong, tough, permanent, and sufficiently elastic to yield when subjected to tensile or to puncturing forces without being injured or destroyed. The present invention is concerned with such a ruflied article and with the novel method and apparatus for its production.

Among the more important objects of the invention are the following: to provide a novel unitary rufiied article made entirely of thermoplastic dielectric material; to provide an unperforated heat-sealed ruflle or rufied article of dielectric material, and one which is free from restricting threads of dissimilar material; to provide a ruffied article wherein the sides of each rulfied area formed in a dielectric thermoplastic material are permanently united to each other and to an adjacent rufiled area, and, if desired, to a base sheet, by a plurality of spot welds to provide a ruflied composite article wherein each individual fold of the rufiie is of uniform size and is spot welded to the base sheet and to an adjacent fold at one or more spaced points of limited area; to provide such a unitary heat-sealed ruflled article which can be elongated more than of its original length without rupturing the rufiied structure or the seam; to provide heatsealed rufiles having stronger bonds between the base sheet and the ruffle and greater resilience along the line of the rufile than ruflied articles made by sewing with thread; to provide novel rufiled articles wherein repairs to the rufiies can be made merely by spot-welding without loss of the ruflied material; to provide in novel manner for the production at high rates of thermoplastic sheetlike articles having permanently united therewith strong welded-on ruffles, uniform and pleasing in appearance, and having good physical properties; to provide a novel process and apparatus for continuously producing thermoplastic articles having welded-0n ruffies while preventing injury to the rufiied material; to provide a novel process and apparatus for welding rufiies of a dielectric material upon a base sheet of such a material by means of a high frequency electric field, while inhibiting arcing at the electrodes and burning of the material; and to provide in novel manner for the continuous spot-uniting of ruffied sheets, films, fabrics or the like made from or containing dielectric thermoplastic materials with other sheets, films, or fabrics made from or containing the same or other thermoplastic dielectric material, either plasticized or unplasticized, or made from paper, cloth and the like materials coated with such a dielectric material.

The invention has especial utility for the production of strong, permanent, yielding rufiies and rufiled articles having elastic properties made from such plasticized thermoplastic materials as the cellulose esters and ethers, such as cellulose acetate, viscose, regenerated cellulose and ethyl cellulose; vinyl resins, such as the polyvinyl chlorides, the polyvinyl acetates, copolymers of vinyl chloride and vinyl acetate, polyvinyl chloride resins, polyvinyl alcohol resins, polyvinyl acetal resins, polymethacrylate resins, and copolymers of vinyl halides and arcylic compounds, such as copolymers of vinyl chloride with acrylonitrile, with acrylic acid, and with the acrylic acid lower alkyl esters; copolymers of butadiene with styrene and with acrylonitrile; and resinous reaction products of a diamine and a dicarboxylic acid.

A preferred form of the novel articles of the invention generally involves a base sheet, silk, fabric or other sheet-like element of a thermoplastic synthetic resin or other dielectric material which is permanently united by one or more series of spaced spot welds with a sheetlike element of the same or other thermoplastic dielectric material having the form of a continuous succession of interconnected folds or rufiies of uniform size and shape.

7 area.

7 effected by the use of localized heat and pressure.

The respective sides. of each folded area are permanently united with each other, with a side of the next adjacent folded area, and with one or more layers of the base sheet by means of at least one spot weld, and preferably two welds, covering. a small portion of each such folded Since the individual folds are not secured by restricting nomelastic sewed threads, the entire body of the welded rufile or the composite article is free. to yield under tension and to elongate or stretch, the extent of such elongation being dependent .upon the character of the material from which the sheet-like elements are made, the number, area and character of the spot welds, and upon other factors. In the case of articles made from sheets of vinyl resins, such as those produced by thezcopolymerization of a vinyl halide with a vinyl ester of a lower aliphatic acid, e. g., a vinyl chloride-vinyl acetate copolymer containing between 70% and 95% ofnthe chloride in the polymer, the heat-sealed ruffled article can be elongated more than 90% of its original length without rupturing the welded seam and, when tension is. released, will regain its original length. The bond between the base sheet and the ruflled sheet is from 60% to 90% stronger than that secured in the same article by sewing with thread.

Since each of the folds is unrestricted by threads, the peakof each fold is free to pucker outwardly from the base sheet and to give to the ruffled article a uniform, pleasing appearance. The folded areas are. not noticeably deformed by the welding heat and pressure used.

' If, when such a rufiied article is subjected to excessive stress, one ormore of the spot welds fails, the rufiles still are held-in place and the appearance and the strength of the ruflled structure are preserved by the remaining spot welds adjacent those which failed.

. The novel ruffled articles are made, in accordance with a preferred form of this invention, by a novel process and apparatus which forms a rapid succession of similar rufiles or folds of the desired size and shape in a sheet-like element of suitable dielectric material and, as rapidly as each such ruffle or fold is formed, the sides of such fold are permanently spot-welded to each other and to a surface of a next adjacent fold, and preferably to one or more'layers 'of a suitable sheet like base element, at from one to two or more spaced points of limited area in such'fol'd. The welding is The heat is produced-locally in the material at each successive folded area by bringing such areas between two electrodes to which a high frequency electric current of suitable voltage is applied, as hereinafter more par- 7 ticularly described.

machine showing the electrodes, electrode reciprocating mechanism, and associated parts, parts being broken away, and other parts being omitted;

Fig. 3 is. a schematic wiring diagram of another high frequency heating circuit and associated parts;

Fig. 9 shows another form of the ruffled composite article;

Fig. 10 shows a unitary rufiled heat-sealed strip reinforced by a folded-over end margin; and

Figs. 11 and 12, respectively show other forms of composite ruflied articles ofthe invention.

Referring to Figs. 1 and 2 of the drawings, the ap-.

12. and prevents turning of the member 11. v s

For passing a high frequency electric current through. a plurality of layers of one or more sheets of thermoplastic organic dielectric material while in the space be: tween the electrodes to heat such material to a welding temperature, the electrodes are in a high frequency electrio circuit which comprises an oscillator or generator 19 or other source of high frequency electric current. One terminal of the high frequency output line is grounded through a line 20. The other terminal is connected with the stationary electrode plate 16 through a coaxial transmission line, the outer conductor 21;: of which terminates in the outer tube 23 of a tuning stub 26 such 7 as shown in Fig. 5. The inner conductor 21 terminates in a coaxial inner rod 23a of the stub 26. A coaxial variable capacitance 24 connects the tube 23 and rod 23a within the said tube. line 25. A short circuiting member 2601 fixes the length of the short circuited stub. The electrode 13 is grounded through a flexible strap 27. V r

For reciprocating each electrode 13 in 'a fixed path toward and from a corresponding stationary electrode 15,'

a standard electric motor 29, equipped with a magnetic brake for instantaneous starting and stopping and of a type commonly used on industrial sewing machines, drives a rotatable shaft 31 through pulleys 33. and 35 and V-belt 37. Shaft 31 drives an upper shaft 39 through pairs of beveled gears 40, 4t). and 41, 41 and vertical shaft 43. Secured upon one end of shaft 39 is a cam plate 45 having a groove in one face providing a cam surface 47. A cam follower 49 is mounted for rotation on a pin secured upon a follower block 51. The latter is secured for vertical adjustment upon reciprocatable rod 11 and has rigidly connected therewith the electrode or electrodes 13. By means of a set screw 52 in block 51 the latter can be secured at a selected point along the rod 11' and thus determine the pressure applied upon the thermoplastic material by each electrode 13 when the latter. is 'in the lowermost i position during a spot-welding operation. A compression Fig. 4 shows diagrammatically the relationship be- 7 tween the actuating cam for thereciprocating electrode and the rotary tuning device of Fig. 3;

Fig. 5 illustrates two alternate forms of tuning stubs or impedance matching means for the high frequency heating circuit; a

Fig. 6 is a fragmentary plan view of a folding and indexing blade for forming the ruffies;

Fig. 7 is a perspective fragmentary view of 'a reciprocatable electrode and operating stem;

Fig. 8 shows one preferred form of ruffied composite article of the invention; 7 1 I spring 53, operatively interposed between'a pin or flange on red 11 and a fixed part of the operating head H, continuously exerts a downward pressure upon the reciprocating rod during operation and prevents backlash.

For feeding a strip or sheet of dielectric material M from a source of supply thereof and for forming a succession of rufiles, or folds therein adjacent the welding or heat-sealing zone a pair of feeder rolls including an idler roll 55 and a roll 56 driven by a. motor 57 draw a sheet of such material from a supply roll 58. The sheet then is directed around a'dance'r roll 61 and idler rolls 6 2, 62

and 62" thence between a fixed margin fold-over guide,

63. It thenis moved intermittently'to the welding zone between the electrodes'13,.15, by means ofa ruffling A mechanism R. The dancer roll 61 is rotatably mounted upon an end of a rod 59 which is pivoted about a fulcrum 60. Mounted on the end of rod 59 opposite roll 61 is an A rider 18 se-. cured to member 11 slides in a groove in a guide member.

Tube 23 is grounded through,

adjustable counterweight, and a mercury switch 64 of wellknown type having terminals connected in the electrical circuit driving motor 57. The arrangement is such that when the roll 61 is in the position shown in full lines in Fig. 1, the switch 64 cuts 055 current to motor 57, and that when roll 61 is in the position shown in broken lines the switch closes the circuit and drives motor 57. Thus, any differences between the rate of unwinding of material from the supply roll and the rate demands of the rufiiing mechanism are equalized.

For feeding a sheet M, with or without a base sheet or film B, of the thermoplastic dielectric material between and past the electrodes at a welding or heat-sealing zone, a resiliently mounted presser foot 67 cooperates with a vertically and laterally movable feed dog 69 while pressingly engaging the sheets interposed therebetween. The feed dog has a serrated surface area adapted intermittently to contact the underside of the ruffied sheet or the composite sheet B and move the same to the left in Fig. 1 away from the welding zone. depressed and Withdrawn from contact with such sheet and moved to the right toward the welding zone. For effecting such feed of the sheet or sheets the presser foot 67 is secured to a rod 68 mounted on the head H for movement toward and from the feed dog 69. An adjustable compression spring 70 presses the foot 67 upon the sheets lying upon the feed dog under a selected pressure. A cam member 71 pivoted on the head H cooperates with a member 72 secured to rod 68 for raising and lowering the rod 68 and for locking it in raised position. For effecting intermittent movement of the feed dog and the sheets lying between it and the presser foot in a direction from the welding zone, as shown diagrammatically in Fig. 1, the feed dog 69 is secured to an arm 73 which is connected with a crank 74 secured upon the shaft 31. The crank arm 73 is pivoted upon an end of a rocker arm 75, the other end of which is pivotally connected with a fixed support. In the form shown in Fig. 2, the feed dog is secured to a plate 76 which has an end pivotally secured to the arm '75. A cam member 77 mounted on shaft 31 cooperates with a cam groove in the plate 76 during rotation of the shaft. The cam member is pivotally connected with arm 75' through arm 73. During operation of motor 29 the rotation of shaft 31 and crank 74 causes the feed dog 69 successively (l) to rise vertically and engage the sheet M or B, (2) to move to the left to index the ruflfled article, then (3) to retract downwardly from the sheet and (4) to move toward the right while disengaged from the latter; and to repeat this cycle of motions for every rotation of shaft 31. The movement of feed dog 69 is timed so that it advances the rufiled article to the left a selected distance just before each forward movement of the foldindexing mechanism to be described.

For forming in sheet M a succession of ruflies of uniform size and spacing at a uniform rapid rate, a crank plate 79 secured upon shaft 39 is operatively connected, by means of a rod 89 and a clevis 81 with a lever arm 82 secured upon a rocker shaft 83 suitably supported on the operating head. When shaft 39 is rotated the rocker shaft 83 oscillates through a selected are, depending upon the position of clevis 81 along the arm 32 maintained by means of a clevis pin cooperating with one of the apertures in arm 82. Secured to an end of rocker shaft 83 is a lever arm 34 which supports an adjustable folding and indexing blade 35. The latter is pivoted upon ears formed on the lever arm 84, and has a rear fiange portion cooper ating with a spring 86 carried by that arm to urge the blade 85 downwa dly against the sheet of material under a regulated tension. The forward end of the blade has a serrated margin and has therein slots 87 (see Fig. 6) adapted to accommodate the electrodes 13, 13. The arrangement is such that blade is held in retracted position to the right (see Fig. 2) away from the electrodes 13 during the welding part of each cycle of operation, and then advances to the left during the part of the cycle when Thereafter the feed dog is electrodes 13, 15 are held apart, thereby moving fresh sheet material into position between the spaced electrodes and forming therein a fold or pleat. A stationary serrated blade prevents retraction of the sheet M when blade 85 is retracted, and prevents folds being formed in sheet B. A folder guide 63 adjacent the folder guide 63 folds over a margin of the base sheet as it moves to the welding zone.

The fold or pleat produced can be varied in size, and the number of folds or pleats per inch can be regulated, by the adjustment of the length of stroke of the arm 84. To increase or to reduce the number of folds per inch, clevis 81 is connected with arm 82 at a point further from or nearer to shaft 83, respectively. Preferably the adjustment is such that from six to eight rufdes or folds per inch are produced, although articles having from four to twelve folds per inch readily are made. However, the rufiied areas should be at least one-sixteenth of an inch in width in order to insure the spot-welding of each rufide at one or more spaced points even in instances where some stretching of the material results from action of the folder blade 85 or of the feeder foot 69.

The actual welding portion of each cycle of operation, during which the electrodes 13, 15, or respective pairs thereof, exert pressure upon the folded-over portions of the ruflie material, and upon the base sheet when present, constitutes about three-fourths of the cycle and is governed by the shape of the cam surface 47. The welding of the rufiied article is accomplished during this time by passing through the layers of material at the spot-welding zone between the electrodes a high frequency current of from 10 to 500 megacycles and at suitable voltages, e. g. around 1,000 volts at 60 megacycles.

In the form of the invention illustrated in Fig. 1 using frequencies of 50 to 500 or more megacycle, the tuning stub 26 of standard construction, the variable capacitance 24 and the interconnecting lines define a matching circuit having impedance that can be varied to accommodate various load impedances and to provide maximum power transfer to the work.

Tuning stubs of the type shown in Fig. 5 are particularly useful as matching sections when employing frequencies of around 100 to 200 or more megacycles. Such tuning stubs are in the form of a coaxial transmission line connected with the high frequency generator. The outer conductor of the coaxial line is a brass tube 90 and the inner conductor is a brass rod 91. Two brass sleeves 93, 94, serve as terminals of the transmission line, one sleeve sliding upon the outer conductor 90 and the other sliding on the inner conductor 91. The length of the short circuited portion is adjusted by means of a brass disc which slides along the inside of the outer tube but also contacts the inner rod 91. The length of the load end is adjusted by sliding the respective terminals 93, 94 along the tube and rod.

In another form of tuning stub illustrated in Fig. 5, the movable shorting disc 95 is replaced by a fixed shorting disc 96 (shown in dotted lines in Fig. 5), so that the length of the short circuited stub is fixed. The points of the transmission line termination at the tube and rod also are fixed. A coaxial variable capacitance 97 (shown in dotted lines) is set within tube 90 and is connected across the conductors 90, 91.

Fig. 3 illustrates schematically a form of circuit particularly useful with frequencies of around 50 to 100 megacycles. It effectively prevents arcing at each electrode 13 as the latter is rapidly withdrawn from the welding zone, by throwing the high frequency circuit out of resonance from a time just prior to the withdrawal of electrode 13 from pressing contact with the work until until after the electrode is in contact with another rufiie in the next succeeding cycle of operation.

If desired, the circuit can be detuned in various ways during such period of each cycle to accomplish this purpose. In the form of the invention shown in Figs. 3 and 4, the circuit comprises a high frequency generator 19 hav- 7 one terminal 20 grounded and having itsother termirial connected in series through line 22 with a'fixed indu ctance 105, a variable condenser V and the lower electrode plate 16. A line 106 having therein a fixed in- I ductance 107 connects line 22 to ground. The condenser V has segmental rotor plates 99 subtending an arc of 90,

mounted upona rotatable shaft 100 havingaan electrically insulated portion 100:: and driven fromshaft 31through a pair of bevel gears 101. Thecondenser has fixed plates 102 with .cutaway segmental portions somewhat :greater than the width of segmental plates 99, and preferably subtending an arc of 120. r g e Fig. 4 more clearly indicates the function of the detuning variable condenser, wherein it is shown in full lines in thejposition during which a'fold is being formed and moved into position betweenthe electrodes and the high frequency circuit is out of resonance. 7 the plates 99 during the welding stage of each cycle is indicated in broken'lines. 'The use of this condenser per- 'One position of mits the use of optimum voltage'during the welding stage of each cycle, whilelimiting the voltage during the balance of the cycle to one insufiicient to cause arcing or burning of the materials.

Fig. '4 also illustrates'the general sh apeof the, rotary cam 47 which, in conjunction with spring 53,. controls the reciprocation of rod 11, and the period of its dwell in -a position with electrodelS. in welding, position. As

shown, this cam and the cam follower-49 raise and lower electrode 13 in a vertical pattern during'one-fourth of a.

cycle, and then, with the aid of'spring 53, hold the electrode in pressure contact with the rufiled material during the balance of each, cycle. Through correlation of the timing of the respective movements of the cam 47, the

folder blade 85' and'the feeder 'foot 69, :the successful production of welded ruffled articles having eight 'ruflies per inch, each ruflie being concurrentlyspot-welded in two the feeder. foot 69 and between'the electrodes, and motor 29 is started. The motor concurrently'actuates the feeder foot 69, reciprocates the electrode 13, and oscillates'the folder .blade 85. Each cycle of operations, during a revolution of cam 47, is as follows: While electrodes 13 are raised from the work and' the presser foot 67 cooperates with feed'dog 69 and 'holds'the several thicknesses of sheets while the ruflier blade 85 scuffsin the rufiie sheet Ma fold perpendicular to' the direction .of feed. Thereafter, while the blade holds the'fold in place 'the upper electrodes 13 descend upon the fold and'hold it, under pressure from spring 53,.while the blade 85 is retracted. The radio freguency'voltage impressed upon" the electrodescauses current to flow through the two walls of each a of the one or more layers of material'forming the folded f area in sheet M and through each layer of the base sheet "B, softening the material and'spot-welding these parts together atone or'more, and preferably two, small spaced welding zones defined by the electrodes, the degree of of plates 99 of the variable condenser V into the position Variations in the rate of application of energy to the w material during the different stages of each cycle of op- V erations also can be effected by modulating the oscillator tube in the high frequency generator, or in any other well-known manner.

One preferred form of spot-weldedruflled articleisil- V, V

' lustrated in Fig.8. In that figure the two sides of each layer of material forming each of the ruflles or folded areas F in the sheet M, one side of each layerforming an adjacent folded area F, and one or more layers of 'thebase welding heat depending upon the voltage across the elecaction advancing each -welded rufiie;before the rather blade forms the next succeeding ruflie. I

,'Theapparatus of Figs. 3 an .4 function similarly to that of Fig. -1, withthe exceptionthat immediately prior to retraction of the electrodes :13- from the welding position the high frequency heating circuit is detuned by movement under any tension exerted either longitudinally or laterally of the rows of spot welds formed. By employing a'folder guide 63 for folding over the margin of sheet M;

and/or a folder guide63'for folding over a margin of sheet B (see Fig; 1), each spot weld unitesfrom four to six or more thicknesses of the'thermoplastic material, as

shown in Fig. 8. Preferably, the folded-over marginal portions of both the sheets M and B are of sufiicient depththat each of the welds formed ina ruflle unite's the J same number of layers of dielectric material as the other weld or. welds. v a The tiny but tough spot welds enhance the appearance of the rufiled article 'while at the same time providing adeof one or more layers of a sheet-like element of a dielectric material has formed therein a succession of closely-spaced folded areas throughout its width and wherein each of one or more layers of a relatively narrow sheetlike base of a dielectric material is permanently'united.

with each of said folded areas by means of one spot Weld located midway between the margins of the sheet-like element. By the use of a somewhat wider sheet-like base, two or more spot welds can be made in each folded area. By using a sheet-like base and sheet-like element ,of different colors, attractive color effects and the efiect of sewing or gathering with colored threads are secured at each spot weld. Thus a ruching or double-ruflie effect is secured in a unitary article. If desired, two or more narrow, longitudinally-spaced, sheet-like bases may be united with the sheet-like element.

7 Permanent unitary ruffles may be made from single sheet-like elements. illustrated in Fig. 10, by using only the sheeting M, the latter is provided with a rufiled margin wherein each fold is spotewelded in place, the welding uniting the two'sides of each ruflledor folded area to each other and to a side of an adjacent folded area. The resultant product may be stored or used as such, or later may be united with a second sheet or film such as the sheet B, in a separate spotwelding or other operation. 7

Fig. 11 illustrates another form'of ruflle which can be produced in accordance with the invention. The ruffles are produced by well-known folder attachments now in use on standard sewing machines. 7 Here each'of the one or more rows of spot welds W unites portions of the sheet M at folded areas through three or more thicknesses Thus, in one form of the invention of the dielectric material. Each folded area consists of a relatively fiat mid-portion 110, two inwardly sloping end portions 111, and two outwardly flaring portions 112, the respective portions being welded together by spaced spot welds arranged in one or more rows. A base sheet B may be spot-welded to the folded sheeting, as in the case of the article shown in Fig. 8.

Fig. 12 illustrates still another form of ruflied article made with the use of the invention in connection with standard ruflling equipment. Here the base sheet B and the ruffled sheet M are spot-welded at one or more spaced points W lying between adjacent ridges.

It will be understood that the invention is not limited to the ruflied articles specifically described, nor to the particular form of the process and apparatus for making the same described. On the contrary, numerous modifications are possible within the scope of the appended claims, whereby a unitary permanent rufiied article is made, and especially one wherein the sides of each ruffled area of each of one or more sheets are spot-welded together and to an adjacent folded area of such sheet at one or more spaced points, and, if desired, to one or more base sheets, and wherein the remainder of the sheet or sheets at each ruflled area is substantially unconfined and is free to yield or stretch under stress.

Either or both of the sheet-like elements of thermoplastic dielectric material may be replaced by a sheetiike element of a non-thermoplastic fibrous material in the form of a Woven, knitted, felted or other fabric impregnated or coated with a thermoplastic dielectric material, and the ruflles formed and spot-welded in the manner herein described. Thus, a woven or knitted fabric made from yarns of cotton, wool, silk, glass or the like may be impregnated and/or coated in whole or in part with a film or body of a vinyl resin or other thermoplastic dielectric material hereinbefore mentioned. Such composite article then is converted into the form of a Welded ruflle or, if desired, is concurrently rutlled and secured to another element of a thermoplastic dielectric material or of a non-thermoplastic material coated with a thermoplastic dielectric material by welding in the manner described. Also useful as the sheet-like elements and/or bases are the composite fabrics made from yarns formed by compositing filaments or fibers of a nonthermoplastic material such as cotton, etc., with filaments or fibers of a plasticized thermoplastic dielectric material.

The term sheet-like element and similar expressions used in the claims are intended to designate sheets, films, webs, batts, and woven, knitted and other fabrics which are relatively small in one dimension.

This application is a division of my application, Serial No. 714,832, filed December 7, 1946 for an invention entitled Heat Sealed Article and Process and Apparatus for Making Same, now matured as Patent No. 2,55 5,409, and it is also a division of my application, Serial No. 190,802 for an invention entitled Process and Apparatus for Making Heat Sealed Ruflied Articles, now Patent No. 2,666,472.

I claim:

1. Process for producing a permanent ruflled article from a sheet-like element of a thermoplastic dielectric material, which comprises intermittently feeding successive increments of such a sheet like element to and through a spot-welding zone while forming in each such increment a folded area interconnected with and closely spaced from the folded area previously formed and, immediately following the formation of each folded area, permanently welding together under action of heat and pressure each of the respective sides of such folded area and one side of a next adjacent folded area then being formed in at least one limited spot welding zone lying within the folded area already formed.

2. Process for producing a permanent ruflled article from a sheet-like element of a thermoplastic dielectric material, which comprises intermittently feeding successive increments of such a sheet-like element to and through a spot-welding zone while forming in each such increment at said welding zone a folded area interconnected with and closely spaced from the next preceding folded area, immediately following the formation of each folded area permanently uniting under action of heat and pressure each of the respective sides of such folded area and one side of a next adjacent folded area then being formed by at least one spot weld employing welding heat produced by a tuned high frequency electric circuit transmitted to such folded area through electrodes, one of which is movable into and out of contact with such area, such welding heat being applied to such folded area during the major portion of the period of dwell of the dielectn'c material at said welding zone.

3. Process for producing a permanently ruffied article, which comprises intermittently conducting to and through a spot-welding zone successive increments of a sheetlike element of a thermoplastic dielectric material and of a sheet-like base of a thermoplastic dielectric material, during each dwell of said element and base at said welding zone forming a folded area in said sheet-like element, immediately thereafter bringing such folded area and an adjacent portion of said base under the influence of a tuned high frequency electric field while exerting pressure upon such folded area and upon the underlying base sheet through electrodes contacting such folded area, thereby producing welding heat in said element and base within said welding zone during the major portion of the dwell thereof at said welding zone and permanently uniting the respective sides of each such folded area with a side of an adjacent folded area being formed and with said base, the major portion of each such folded folded area being unwelded and free to yield under stress, and discontinuing the welding heat and pressure.

4. Process for producing a permanently rulfied article, which comprises intermittently moving to and through a spot-Welding zone successive increments of a sheet-like element of a thermoplastic dielectric material and of a sheet-like base of a thermoplastic dielectric material, during each brief dwell of said element and base at such welding zone forming in said element a folded area immediately adjacent a similar folded area formed during the preceding dwell of said element at said Zone and superposing the newly formed folded area upon said base, thereafter during such'dwell of said element and base at the welding zone pressing a portion of such folded area upon the underlying base while subjecting such portion to the action of a tuned high frequency electric circuit, thereby heating selected portions of such folded area and of the underlying base to a welding temperature during at least two-thirds of the period of dwell of the folded area at the spot-welding zone and permanently uniting the respective sides of such folded area with each other, with a side of an adjacent unfolded area, and with the said base within a minor portion of the total area 'of such folded area, the balance of each folded area being unwelded and free to yield under stress, immediately thereafter discontinuing the application of welding heat and pressure, removing the thus welded folded area from the welding zone and moving another increment of the sheet-like element and of said base to said spot-welding zone.

5. Process for producing a permanent rufiied article from a sheet-like element of a thermoplastic dielectric material, which comprises intermittently feeding successive increments of such a sheet-like element to and through a spot-welding zone while forming in each such increment a folded area interconnected with and closely spaced from the folded area previously formed and, immediately following the formation of each folded area and during the dwell of said sheet-like element between successive feeding movements thereof, permanently welding together under action of heat and pressure each of the ii i respective sides-of such folded area and one side of a next adjacent folded area then being formed in at least one limited spot-Welding" zone lying within the folded area being formed and narrower than said folded area.

6. Process for producing a permanent rufiied article, which comprises intermittently conducting to and through a spot-welding'zone successive contacting increments of a sheet-like element and of a sheet-like base of thermoplastic dielectric material, during each dwell of said element and base at such" welding zone forming a folded area in said sheet-like element, and immediatelythereafter during such dwell permanently uniting the respective sides of such folded area to each other and to said base by means of at least one spot weld. by heat induced in such dielectric materiaL the major portion of each such folded area surrounding such spot weld being unwelded and free toyield under stress.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Hoyler An Electronic Sewing Machine Reprint from the August 1943. issue of Electronics (7 pages, page 6 in particular). 7

Brown July 26, 1949 

1. PROCESS FOR PRODUCING A PERMANENT RUFFLED ARTICLE FROM A SHEET-LIKE ELEMENT OF A THERMOPLASTIC DIELECTRIC MATERIAL, WHICH COMPRISES INTERMITTENTLY FEEDING SUCCESSIVE INCREMENTS OF SUCH A SHEET-LIKE ELEMENT TO AND THROUGH A SPOT-WELDING ZONE WHILE FORMING IN EACH SUCH INCREMENT A FOLDED AREA INTERCONNECTED WITH AND CLOSELY SPACED FROM THE FOLDED AREA PREVIOUSLY FORMED AND, IMMEDIATELY FOLLOWING THE FORMATION OF EACH FOLDED AREA, PERMANENTLY WELDING TOGETHER UNDER ACTION OF HEAT AND PRESSURE EACH OF THE RESPECTIVE SIDES OF SUCH FOLDED AREA AND ONE SIDE OF A NEXT ADJACENT FOLDED AREA THEN BEING FORMED IN AT 